Perform ACC Calibration: It is *very* important that the MK is as horizontal and still as possible, shim it up so the arms are perfectly level, then program EEPROM by moving left stick to upper right corner. (max throttle + max right yaw)- you'll hear audible confirmation. ACC only needs to be calibrated once, after that you can start from an embankment or sloping surface without problems. The saved values will be loaded at every bootup.